CO-Horts

CO-Horts

Thursday, February 9, 2017

How about a little R-E-S-P-E-C-T?

Posted by Kelley Rawlsky, Broomfield County Extension

Hello! My name is Kelley and I’m a biophiliac. A
what? A biophiliac. Okay, so technically that may or may not be a
real word. E.O. Wilson, Professor
Emeritus at Harvard University, coined the term “biophilia” in his book titled
the same in 1984. There are many
definitions of biophilia, but the most simple is “a love of all living
things”. Dr. Wilson’s theory is, in
part, that humans are genetically predisposed to derive psychological and
physiological benefits from nature. In his book, Biophilia, he states “to the degree that we come to understand
other organisms, we will place a greater value on them, and on ourselves”.

Now that we’ve been properly introduced, I want
to share some amazing qualities our phytocompanions possess and why I think
they deserve a little more R-E-S-P-E-C-T.
Not sure phytocompanions is in the dictionary either, but my blog today,
so my rules?

Did you hear the one about the plant that walked
over to the water spigot? Of course not,
because plants aren’t able to go get a drink of water, no matter how many days
or weeks we’ve neglected them. Plants
also can’t move underneath the patio during a hailstorm. Nor can they relocate themselves three feet west
of the Autumn Blaze maple you planted five years ago that is now blocking their
sunlight.

Plants are constantly interacting and adapting
to their environments. Here are a few
cool examples.

Heliotropism, also known as solar-tracking, is
the ability for a plant to follow the direction of the sun on a daily
basis. Sunflowers are probably the most
famous example of heliotropism. Some
studies suggest sunflowers and other solar-tracking plants do this to increase
light absorption, photosynthetic efficiency, and increase crop production. The
snow buttercup, Ranunculus adoneus,
is a subalpine and alpine plant native to our higher elevations here in
Colorado. Heliotropism in the snow
buttercup is believed to occur, at least partly, to create warmth in the
interior of the flower to make a warm, cozy landing zone for pollinators.

Phototropism is the reason everyone who has
houseplants near windows has to rotate them, or at least should rotate them, on
a regular basis. The plants start
growing towards the light, right?

Gravitropism is another interesting plant response. Have you ever planted a tomato in a trench on
its side? Isn’t it amazing how the plant
“knows” that the shoot growth needs to go upwards to photosynthesize and the
roots need to grow down for water and mineral uptake?

What about that cute, little Virginia creeper, Parthenocissus quinquefolia, you planted
eight years ago that started climbing on everything in sight and is now trying
to take over your house? This is an
example of thigmotropism -- not the attempted coup d’etat part, but the fact that
a plant can respond to touch or contact in its environment. Yes, a plant has a
“sense of touch”, of sorts.

As you have likely discovered by now, tropism in
horticulture generally refers to the response of a plant to an environmental
stimulus. It’s when a plant moves towards or away from a stimulus, which could
be something like touch, gravity, light or even weather events.

Plant growth regulators such as auxin are
responsible for this behavior. For
example with phototropism, auxins will accumulate on the side of the stem or
leaf that is away from the light source to encourage elongation. The plant then grows more on the dark side
than the side receiving the light. This
redirects the stem or leaf towards the light source.

So, back to Dr. Wilson and his biophilia theory
-- the extent that we understand other organisms, we will place a greater value
on them. I hope you have a better
appreciation and understanding for just a few of the many, many ways our
phytofriends are constantly interacting with their sometimes very challenging
environments. Maybe the next time you
turn that hanging ivy plant away from the window or you drive past a field of
sunflowers, you will take a moment to observe and ponder the amazing world of
plants.

Suggested reading: Monica Gagliano’s research on
mimosa plants where the plants appeared to have “learned” new behaviors. She is
a Research Associate Professor at the University of Western Australia.